[46.03] The VLA Upgrade

R. A. Perley (NRAO)

The National Radio Astronomy Observatory (NRAO) has formally organized
the VLA Upgrade Project, with the immediate goal of producing, by
mid-1997, a design study of upgrading the VLA to a state-of-the-art
instrument. The design study will examine in detail a wide range of
suggested improvements to the VLA's capability, including (but not
limited to):

1. Retrofitting existing receivers with improved low-noise devices,
and increasing the instantaneous bandwidth available for correlation
to at least two GHz, while adding new frequency bands, centered near
2.7 and 33 GHz, extending the 21-cm band from the current limit of
1270 MHz to as low as 1000 GHz, and replacing the current
low-frequency system with a wide-band prime focus system capable of
continuous coverage from approximately 250 MHz through 1000 MHz.

2. Replacing the current LO/IF waveguide transmission system
with a fiber-optic system capable of at least 2 GHz bandwidth, plus a
new correlator, providing up to 8192 spectral channels from at least
33 antennas.

3. Addition of at least four new, fixed antennas. These, and at
least two nearby VLBA stations will be connected by fiber to the new
correlator to define a new 'A+' configuration with 8 times the
resolution of the current VLA.

Implementation of these improvements would give astronomers a radio
telescope capable of high fidelity imaging over a resolution range of
2500, with nearly continuous frequency coverage between 250 MHz to 50
GHz, to a sensitivity (between 2 and 30 GHz) of better than 3\muJy
in 12 hours. The new correlator would provide unprecedented spectral
resolution and flexibility. The new antennas would be used alone with
the VLBA when the VLA is in its shorter configurations, resulting in a
vast improvement in the VLBA's imaging capability, and complete
elimination of the 'VLA-VLBA gap'.